This invention is an implantable vaso-occlusive coil which is implanted using minimally invasive surgical techniques. It is a complex, helically wound coil made up of a primary helically wound coil which is then wound into a specific secondary shape. The secondary shape is itself a series of helical turns. At least a portion of the turns in the secondary shape form a cylindrical region and adjacent that region on at least one end is a conical region which tapers from a diameter approximating that of the central cylindrical region to a smaller diameter. The device is desirably self-forming upon exit from the distal end of a delivery catheter. Also, the conical tipped vaso-occlusive device may also utilize thrombus-enhancing filamentary material.
Vaso-occlusive devices are surgical implements or implants that are placed within some opening in the human body. Typically the opening is either within the vasculature or some other region which is to be occluded. Such other sites include fallopian tubes and bile ducts. They are delivered typically via a catheter. It is intended that the devices either block the flow of blood through a vessel making up that portion of the vasculature via the formation of an embolus. An embolus may also be formed within an aneurysm stemming from a normal vessel by use of this invention.
One such widely used device is the helically wound vaso-occlusive coil. Many such coils are dimensioned to engage the walls of the vessels or other sites they are intended to occlude. Other significantly less stiff helically wound devices have also been described in the literature.
A patent describing an early vaso-occlusive device which patent, parenthetically, also provides an excellent background to the vaso-occlusive technology at that time is Ritchart et al. (U.S. Pat. No. 4,994,069). Ritchart et al. describes a vaso-occlusive coil that assumes a linear helical configuration when stretched and a folded, convoluted configuration when released from the catheter. The stretched condition is used in placing the coil at the desired site via passage through the catheter. The coil assumes a relaxed configuration-which is better suited to occlude the vesselxe2x80x94once the device is released from the catheter. Ritchart et al describes a variety of secondary shapes including xe2x80x9cflowerxe2x80x9d shapes and double vortices.
The use of vaso-occlusive coils having attached fibrous elements in a variety of secondary shapes is shown in Chee et al. (U.S. Pat. No. 5,304,194). Chee et al. describes a helically wound device having a secondary shape in which the fibrous elements extend in a sinusoidal fashion down the length of the coil. These coils, as with the Ritchart et al. coils, are produced in such a way that they will pass through the lumen of a catheter in a generally straight configuration and, when released from the catheter, form a relaxed or secondary shape in the lumen or cavity chosen within the human body. The fibrous elements shown in Chee et al. enhance the ability of the coil to fill space within the vasculature and to facilitate formation of an embolus and subsequent allied tissue.
There are a variety of ways of placing shaped and linear coils into the human vasculature. In addition to those patents which are believed to describe only the physical pushing of a coil out into the vasculature, (e.g., Ritchart et al.), there are a number of other ways to release a coil at a specifically chosen time and site. For instance, U.S. Pat. No. 5,354,295 and its parent U.S. Pat. No. 5,122,136, both to Guglielmi et al. describe a device which is electrolytically detachable from its pusher wire.
A variety of mechanically detachable devices is also known. For instance, U.S. Pat. No. 5,234,437, to Sepetka, shows a coil which is helically unwound from a pusher having an interlocking surface. U.S. Pat. No. 5,250,071, to Palermo, shows an embolic coil assembly using interlocking clasps mounted both on the pusher and on the embolic coil. U.S. Pat. No. 5,261,916, to Engelson, shows a detachable pusher-vaso-occlusive coil assembly having an interlock ball and keyway-type coupling. U.S. Pat. No. 5,304,195, to Twyford et al., shows a pusher-vaso-occlusive coil assembly having an affixed, proximally extending wire carrying a ball on its proximal end and a pusher having a similar end. The two ends are interlocked and disengage when the coil is ejected from the distal end of the catheter. U.S. Pat. No. 5,312,415, to Palermo, shows a multiple coil device in which the coils are placed on a single pusher in the form of a guidewire which has a section capable of interconnecting with the interior of the helically wound coil. U.S. Pat. No. 5,350,397, to Palermo et al., shows a pusher having a throat at its distal end and a pusher through its axis. The pusher sheath will hold onto the end of an embolic coil and the embolic coil will then be released upon pushing of the axially placed pusher wire against the proximal portion of the vaso-occlusive coil.
Vaso-occlusive coils having little or no inherent secondary shape have also been described. For instance, in U.S. patent application Ser. No. 07/978,320, filed on Nov. 18, 1992, entitled xe2x80x9cUltrasoft Embolism Coils With Fluid-Like Propertiesxe2x80x9d by Berenstein et al. is coil having little or no shape after introduction into the vascular space.
A variety of other patent applications assigned to Target Therapeutics, Inc., of Fremont, Calif. describe coils or other related vaso-occlusive devices having specific shapes. Of particular interest is U.S. design patent application Ser. No. 29/037,001 filed Mar. 31, 1995 for spiral vaso-occlusive coils by Mariant et al.
None of these previously-described devices or self-forming helically wound coils which self-form into secondary structures having opposing conical end separated by a generally cylindrical portion between those opposing ends.
This invention is a vaso-occlusive device comprising a helically wound coil which is formed by winding a wire into a first helix or form; the first helix is then itself wound into a secondary form. The secondary form is one which, once ejected from a delivery catheter, forms a shape having conical section at each opposing end, which conical end diameter decreases to the furthermost points of the device. It generally forms a xe2x80x9csubmarinexe2x80x9d type shape. Desirably, the vaso-occlusive device is of a size and shape suitable for fitting within a vascular cavity (e.g., an aneurysm, perhaps, a fistula). Stiffness of various parts of the coil may be tailored or selected to enhance the ability of the device for its specific applications. Fibrous materials may be woven into the member or tied or wrapped onto it.
The device may be made in a variety of ways. Typically, the member is helically wound in a generally linear fashion to form a first or primary winding. After completion of that step, the primary winding is then wound around an appropriately shaped winding fixture or form and the so-wound assembly is heat treated to help it retain its shape after removal from the winding fixture. Auxiliary fibrous materials are then added by weaving, tying, or other suitable permanent attachment methods.
The device is used simply by temporarily straightening device and introducing it into a suitable catheter, the catheter already having been situated so that its distal opening is within the mouth of the vascular cavity or opening to be filled. The device is then pushed through the catheter and, upon its ejection from the distal end of the catheter into the vascular cavity, assumes its relaxed shape.
The device is typically used in human vasculature to form emboli but may be used in any site in the human body or occlusion such as one produced by the inventive device is desirable.